The present invention relates to air separation modules, and in particular, to air separation modules for use in aircraft applications.
On-board air separation modules can be used to create an inert environment in various locations on an aircraft, such as in the cargo area or fuel tanks. Air separation modules can produce nitrogen-enriched air using molecular sieve technology or hollow fiber membrane technology. For example, an air separation module may contain a plurality of hollow fibers that separate compressed air into a nitrogen-enriched portion and an oxygen-enriched portion. The compressed air source can be compressed RAM air or can be bleed air taken from the compressor section of the aircraft engine. In one type of air separation membrane, compressed air is fed into one end of the bore side of the hollow fibers and as the gas travels the length of the fiber, oxygen permeates through the fiber wall at greater amounts than nitrogen, is collected, and is dumped into an ambient environment. The gas exiting the hollow fibers therefore becomes oxygen-depleted or nitrogen enriched.
The nitrogen-enriched air produced by the air separation module can be directed to the fuel tanks of the aircraft. Nitrogen-enriched air is supplied to the fuel tanks in a sufficient quantity to maintain the oxygen concentration in the fuel tank below a specified amount in order to limit the flammability of the fuel tanks.